Palos Verdes, CA, USA
N294T
Piper PA-18-105
During a banner towing flight over the ocean along the coast, the engine lost power and the airplane ditched in the water. While in cruise flight, the engine began to run rough and lose a significant amount of power. The pilot attempted corrective measures (applying and removing carburetor heat and releasing the banner), but the airplane continued to lose power. The engine was not producing enough power for continued flight and the pilot landed in the water short of the beach. When the airplane hit the water, it nosed over and came to rest inverted. Post accident examination revealed that the number 4 piston had fractured around the circumference of the piston just above the connecting rod pin and had beach mark signatures consistent with cyclic fatigue. Fractured pieces of the piston were found in the oil sump. The aft piston pin end cap was worn and burnished. The forward piston pin end cap separated from the piston pin, with fracture surface signatures consistent with overload. The rod journal bearing was also worn and burnished. The number 4 connecting rod journal of the crankshaft was cracked and the connecting rod cheek on the crankshaft was fractured perpendicular to the rod journal. The journal cheek fracture exhibited beach marks consistent with cyclic fatigue. The fracture had an irregular shape that provided a "key" that maintained rotational continuity of the crankshaft during operation; however, the fracture also allowed the crankshaft to flex. Flexing of the crankshaft induced a rotational misalignment of the connecting rod, which in turn induced the cyclic fatigue failure of the piston. This condition was likely on-going for some time prior to the final fatigue failure. Copious amounts of small metal debris and flakes were retrieved from the oil pressure filter screen that were consistent with the rod end cap bearing material and should have been apparent if the screen and filter were being checked for contaminants on a regular basis. Lycoming Mandatory Service Bulletin (SB) No. 480E recommends an oil change, pressure screen cleaning and oil sump screen check at 25-hour intervals. The SB continues that observation of abnormal metal content during the service may indicate additional service is required. Examination of maintenance records revealed that it had been 112 hours since the last 100-hour inspection at the time of the accident. The aircraft and engine logbooks contained no record of the operator following the recommended procedures as set forth in SB 480E.
HISTORY OF FLIGHT On August 20, 2005, about 1420 Pacific daylight time, a Piper PA-18-105, N294T, experienced a loss of engine power and ditched into the water near Lunada Bay, Palos Verdes, California. Van Wagner Aerial Media LLC, was operating the airplane under the provisions of 14 CFR Part 91. The commercial pilot, the sole occupant, was uninjured; the airplane was destroyed. The local banner towing flight departed Long Beach Daugherty Field Airport, Long Beach, California, at 1205. Visual meteorological conditions prevailed, and no flight plan had been filed. The approximate global positioning system (GPS) coordinates of the primary wreckage were 33 degrees 46.200 minutes north latitude and 118 degrees 25.000 minutes west longitude. In a statement to the National Transportation Safety Board investigator-in-charge (IIC), the pilot related that while flying southbound along the coast in the area of Lunada Bay, about 1,000 feet mean sea level (msl), and approximately 200 to 300 hundred feet offshore, the engine started to run rough. He attempted to correct the abnormality by applying carburetor heat, but that made the engine lose more power. He turned off the carburetor heat. The engine rpm (revolutions per minute) increased, but the airplane continued to descend. While still over the water, he released the banner. The pilot thought the release of the banner would enable him to divert to Zamperini Field Airport (TOA), Torrance, California, and make an emergency landing. The airplane continued to descend, and the pilot made a forced landing into the water. During the impact sequence, the airplane nosed over and came to rest inverted. PERSONNEL INFORMATION A review of Federal Aviation Administration (FAA) airman records revealed that the pilot held a commercial pilot certificate with ratings for airplane single engine land and airplane single engine sea. He also held private pilot privileges for airplane multiengine land and glider. The pilot held a second-class medical certificate issued on November 29, 2004, with the limitation that the pilot must wear corrective lenses. The operator reported that the pilot had a total flight time of 3,547 hours. He logged 263 hours in the last 90 days, and 58 in the last 30 days. He had an estimated 838 hours in the accident make and model. He completed a biennial flight review on May 7, 2004. AIRCRAFT INFORMATION The airplane was a Piper PA-18-105, serial number 182408. A review of the airplane's logbooks revealed that the airplane had a total airframe time of 12,589 hours at the last 100-hour inspection that was completed on March 29, 2005. The logbooks contained an entry for an annual inspection dated December 3, 2004. The tachometer read 7,694 at the last inspection. The tachometer read 7,806.20 at the accident scene. The engine was a Textron Lycoming 0-360-A1A, serial number L-4673-36. Total time recorded on the engine at the last 100-hour inspection was 6,078 hours, and time since major overhaul was 473 hours. Examination of the maintenance records revealed that it had been 112 hours since the last 100-hour inspection at the time of the accident. The engine logbook and aircraft logbook contained no record of the operator following the manufacturer's recommended procedures, pursuant to Lycoming Mandatory Service Bulletin (SB) No. 480E, regarding the cleaning of the oil screen and oil screen content inspection. TESTS AND RESEARCH The National Transportation Safety Board, the FAA, and Textron Lycoming, a party to the investigation, examined the wreckage at Aircraft Recovery Services, Littlerock, California, on August 25 and 26, 2005. During the visual examination of the engine, investigators noted internal damage to the engine, which precluded an engine run. Three pistons and rods were still connected to their respective crankshaft journal. The investigators focused on the number 4 cylinder and piston assembly. The number 4 piston remained captured in the top area (outboard) of the cylinder bore and was fractured around the circumference of the piston parallel to the piston pin bore. The Lycoming representative reported that the fracture surface in the area of the piston pin bore material revealed "bench mark" signatures consistent with cyclic fatigue. The associated surrounding areas exhibited fracture surface signatures consistent with overload. The fractured pieces of the piston were found in the oil sump. The number 4 connecting rod remained attached at the associated crankshaft journal. The piston pin was intact and remained situated in the respective bore end on the connecting rod. The Lycoming representative described the aft piston pin bushing, situated in the bore end of the connecting rod, as excessively worn and burnished. The forward piston pin bushing was broken off at the section that protrudes into the inner diameter of the piston pin. The fracture surface signatures at the broken off piece were consistent with overload. No significant heat distress signatures were noted at the reciprocating end of the connecting rod. According to the Lycoming representative, there was also an excessive amount of fore and aft play with respect to connecting rod end and crankshaft journal clearance, which was inconsistent with manufacturer specifications and standard practices. The connecting rod did not track along the required rotational plane needed for continued operation. The connecting rod cap bolts were securely fastened. The connecting rod bolts and their respective caps were removed. The Lycoming representative described the subject connecting rod journal bearing as excessively worn and exhibited a burnished appearance at the forward facing section of the bearing. The Lycoming representative opined that the condition of the bearing material and associated wear patterns indicated that this condition had existed for an extended period of time. Copious amounts of small metal debris and flakes were retrieved from the oil pressure filter screen during its disassembly. Examination of the number 4 connecting rod journal of the crankshaft revealed a crack. The crankshaft was cracked and separated perpendicular to the rod journal along the forward cheek of the crankshaft throw. The separated pieces formed an irregular interface maintaining rotational continuity of the crankshaft. During the investigation, the case halves were separated, and the crankshaft was removed for further examination. The separate surfaces of the crankshaft fracture exhibited "beach marks," which the Lycoming representative said was consistent with cyclic fatigue. Investigators reoriented the broken pieces and noted that an uneven burnished section existed on the rod journal where the connecting rod bearing would make contact with the rod journal. The burnished area coincided with the bellmouthed area of the respective connecting rod bearing. The Lycoming representative opined that these signatures would indicate that the crankshaft was "flexing" during operation and would illustrate the existence of an on-going pre-accident condition. Lycoming SB No. 480E provides instruction for oil and filter change and screen cleaning and oil filter/screen content inspection. The SB recommends that an oil change, pressure screen cleaning, and oil sump screen check occur at 25-hour intervals. The SB reads that "If examination of the pressure screen and the oil sump suction screen indicates abnormal metal content, additional service may be required to determine the source and possible need for corrective maintenance." ADDITIONAL INFORMATION The IIC released the wreckage to the owner's representative.
a loss of engine power due to the cyclic fatigue failure and separation of the number 4 piston.
Source: NTSB Aviation Accident Database
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